1. Field of the Invention
The present invention relates generally to seat integrated recliner latch assemblies and, more particularly, to an improved recliner latch assembly incorporating a radially shiftable and yielding pawl in combination with a fixedly positioned wedge block for creating an upward force on the pawl so as to maintain a toothed engagement with a rotatable seatback.
2. Description of the Prior Art
The prior art is well documented with examples of vehicle seat recliner mechanisms and, in particular, those which employ some form of inertial locking or restraining mechanism responsive to a determined force exertion and for the purpose of maintaining the seat back in an upright locked position. U.S. Pat. No. 5,163,735, issued to Aljundi, discloses an inertia latch for a vehicle seat backrest which includes a wheel having a pinion gear formed thereon and which engages sector plate teeth of a backrest bracket portion. As the backrest is shifted on rapid deceleration, the wheel rapidly drives a locking tooth into engagement with a locking pawl at the lower end of the inertia pendulum. The inertia pendulum is rotated upon application of an inertial load into an interlocking relationship with the locking tooth. A tilt control pinion gear engages a tilt sector plate to adjust the orientation of the seat back relative to the seat bottom.
U.S. Pat. No. 4,082,353, issued to Hollowell, teaches another variation of an inertia-responsive vehicle seat back latch mechanism for a vehicle seat assembly and including a seat back pivotally supported for forwardly tilting movement. The latch mechanism includes a seat back stud movable with the seat back, a locking pawl pivotally attached to the seat cushion support which is adapted to engage the seat back stud, and a latching pawl pivotally attached to the seat cushion support for preventing rotation of the locking pawl. The locking pawl is disposed to engage the seat back stud, but is cammable free of the seat back stud thereby allowing forward tilting of the seat back. During a vehicle deceleration greater than a predetermined value, the latching pawl prevents rotation of the locking pawl by engaging the locking pawl with the seat back and preventing forward tilting of the seat back.
Additional examples of vehicle seat back inertial locking devices are illustrated by U.S. Pat. No. 5,460,429, issued to Whalen, and U.S. Pat. No. 4,225,177, issued to Klutting. U.S. Pat. No. 5,328,241, issued to Haider, teaches a recliner for a vehicle seat assembly in which the locking pawl of the recliner is formed with teeth configured to resist damage when the seat back is rotated to a forward dump position. The pawl teeth are disclosed as being progressively longer, from the end of the pawl inward, over a selected number of teeth and so that the teeth resist bending deformation caused by impact with the latch gear end face.
The present invention is a novel seat integrated restraint latch assembly with built-in inertial locking mechanism for maintaining a seat back of the seat in an upright position responsive to an experienced inertial load (also referenced as a xe2x80x9ccrash loadxe2x80x9d). Applicant further believes the design of the instant invention to set a new industry standard of load capability for a belted seat back latch/recliner mechanism.
A frame includes a lower support bracket secured to a floor of the vehicle and an upwardly extending arm hingedly connected to the support bracket and defining part of a seat back of the vehicle seat. The extending arm is preferably reinforced proximate the hinged connection and so that, upon experiencing the inertial load, engages against and extending flange of the support bracket to prevent the arm from bending. A spring biased latch gear is mounted to the arm at the hinged connection and includes an exterior facing surface defined, in part, by a first plurality of teeth.
A first cam is actuated by a lever projecting from a side of the lower support bracket of the seat frame. The first cam is pivotally secured to the support bracket at a first specified location and is spring biased in a selected rotation direction. A second cam is likewise pivotally secured to the support bracket at a second location. The first and second cams are configured with associated recessed and extending finger portions such that, upon actuation and rotation of the first cam in a given direction, the second cam is influenced to rotate in an opposite direction.
A pawl is pivotally secured to the support bracket at a third location and is engageable by one or both of the first and second cams. The pawl includes a second plurality of teeth arrayed in opposing fashion relative to the first plurality of teeth of the latch gear. The pawl further includes an extending end configuration further defined by an upwardly and arcuately extending surface.
A wedge block is fixedly secured to the support bracket at a fourth location. The wedge block includes, in the preferred variant, first and second shoulder support shoulder support surfaces which are configured in a stepped arrangement in opposing fashion to the extending end configuration of the pawl. The extending end configuration of the pawl engages upon the first support surface of the wedge block upon being rotated from a first latched position to a second disengaged position and at which point the seat back may be rotationally readjusted relative to the support bracket and seat bottom.
An elongated interior channel is defined within the pawl and includes a first substantially circular shaped section and a second substantially circular shaped section communicating with the first circular section by a narrowed boundary disposed therebetween. A fixed pin projects from the support bracket and through a first selected section of the interior channel. The pin radially and forcibly shifts across the narrowed boundary responsive to the experienced inertial (or crash) load and shifts the pawl in a lateral direction so that the extending end configuration engages upon the second and succeeding shoulder support surface. At this point, the second arrayed plurality of teeth of pawl are forcibly pressed into inter-engaging contact against the first plurality of teeth of the latch gear. Additional upward engagement against the pawl is further contributed by the first and second cams in the deformed and inertial loaded position.